JPS61199232A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium which is improved in the crystal orientability and magnetic characteristics of a magnetic medium layer, increases the number of times of CSS and has a good squareness ratio by providing a specific nonmagnetic underlying layer on a nonmagnetic substrate via a nonmagnetic hardened layer and providing the magnetic medium layer on the underlying layer. CONSTITUTION:The nonmagnetic hardened layer 2 consisting of an alumite film, etc. is formed on the nonmagnetic substrate 1 consisting of an aluminum alloy, etc. and the surface thereof is finished to a specular surface to improve the surface hardness and accuracy of the substrate 1. The nonmagnetic underlying layer 3 is then formed by sputtering one kind among Si, Ti, Mo, W and Zr on the layer 2 within a range of 50-2,400Angstrom thickness. The ferromagnetic medium layer 4 consisting of gamma-Fe2O3, Co, Co alloy, etc. is formed on the layer 3. The crystal orientability and magnetic characteristics of the magnetic medium are made better by providing the layer 3 than in the case of providing directly the magnetic medium layer 4 on the layer 2. The number of times of CSS is thus increased and the high reliability magnetic disk or the like is obtd.

Description

[Detailed description of the invention] [Field of use in dwarf industry] This invention is applicable to cobalt and cobalt alloys.

Metals such as iron, iron alloys, nickel, nickel alloys, etc.
! The present invention relates to a magnetic recording medium having a magnetic layer made of an I magnetic material or a magnetic layer made of a metal oxide'is material such as iron oxide or chromium oxide.

[Conventional technology]

In recent years, the importance of external storage devices such as magnetic disks in computer systems has increased, and the demand for higher recording densities is increasing.

A magnetic recording device is composed of the main components of a recording/reproducing head and a magnetic disk.The magnetic disk rotates at high speed, and the recording/reproducing head floats a minute distance above the magnetic disk.

As the performance of magnetic recording devices improves, the load on the recording/reproducing head is reduced in order to reduce the flying distance, and contact start/stop (C)
55) type head flotation system is adopted. In order to increase the recording density and performance of magnetic disks, that is, magnetic recording media, it is necessary to make the recording media thinner, more uniform, and improve the magnetic properties (improvement of coercive force and squareness ratio).

In addition, it is necessary to improve disk surface precision and head crush resistance in order to ensure stable head lift conditions at low flying heights and prevent head-disk collisions (head crashes).

Accordingly, it has become important to improve the quality of the substrate that supports the magnetic medium layer.

Conditions for a substrate suitable for high-density recording include good mechanical flatness and surface roughness, and a small number of defects. Furthermore, as the recording medium becomes thinner, the substrate needs to have sufficient hardness. In other words, if the substrate is soft, it will cause deformation such as depression when the magnetic head is connected to the magnetic disk, and not only will it be impossible to obtain a stable floating state of the 6B air head, but also the contact start stop, which indicates the reliability of the magnetic recording device. (aSS) There is a problem that the number of times becomes small.

Conventionally, aluminum alloy has been used for the substrate of magnetic tinuku, but this is due to surface hardening and surface precision.

On top of that, a hardened layer is cut out. For this hardened layer, N1-P plated film or alumite film with good abrasiveness has been used (for example, Electric Corporation Research and Practical Application Report Vol. 31 No. 9 1731-1744, Prior Art Patent Application No. 1983- 8863
No. 3, Japanese Patent Application No. 59-111468).

After forming this film, &machining is performed to improve the surface accuracy.
forming a magnetic medium layer; There is a close relationship between the magnetic properties and crystal orientation of the magnetic medium layer, and it is known that the crystal orientation is influenced by the type of underlying film of the magnetic medium layer (for example, Ota et al. Japanese Society of Applied Magnetics, Abstracts of Academic Lectures, 15pR-a (1984)). For example, r
It is known that magnetic properties are better when Fe2O3 thin films are oriented with [111] orientation, and when 00 and 00 alloy thin films are oriented with C axis.

[Problem that the invention seeks to solve]

However, when two types of hardened layers are formed to form a magnetic medium layer, the desired crystal orientation is achieved in most cases, and as a result, the magnetic properties change, such as the squareness ratio S'' determined from the magnetization curve. The problem was that it didn't get better.

This invention was made to solve the above-mentioned problems.
The object of the present invention is to obtain a highly reliable magnetic recording medium in which the l number increases.

[Means for solving problems]

This magnetic recording medium has a nonmagnetic underlayer made of any one of Si, Ti, MO, W, and Zr formed between a nonmagnetic hardened layer and a magnetic medium layer.

[Effect]

si, Ti, MO, W, and Zr according to this invention
By forming a non-magnetic underlayer made of one of these, it is possible to prevent the adverse effects of the non-magnetic hardened layer, improve the crystal orientation of the magnetic medium layer, and improve the hardness and surface precision of the non-magnetic hardened layer. Good properties are not diminished.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) is an aluminum alloy substrate which is a nonmagnetic substrate, (2) is a nonmagnetic hardened layer, (3) is a Si nonmagnetic underlayer, and (4) is a magnetic medium layer.

The present invention will be explained in more detail with reference to specific examples below, but the present invention is not limited thereto.

EXAMPLE An alumite film having a thickness of 4 μm was coated as a non-magnetic hardened layer (2) on a Dinuk-shaped aluminum alloy substrate (1). After mirror-finishing the alumite film, a Si film was formed as a nonmagnetic underlayer (3) by reactive sputtering.

Furthermore, an rFe2O3 thin film was formed as a magnetic medium layer (4).

Samples with different Si film thicknesses were prepared and nine different measurements were performed, and the results are summarized in the table. For crystal orientation, xl
Measured by IM diffraction method, the peaks in the 222 direction of r Fe2n5 (spinel type) + (222) and 3
It was expressed by the ratio of peak I (311) in 11 directions.

The squareness ratio of 8 was determined from the magnetization curve. .

Furthermore, $2 Figure K shows an example of changes in the thickness of the non-magnetic underlayer and each characteristic value when the non-magnetic underlayer is 8i.

An example in which the nonmagnetic underlayer is made of Ti is shown in FIG. In the figure, 2 curves 11 represent changes in I (222)/summer (311), 1 curve 12 represents changes in S'', and 9 curves 13 represent changes in the ratio of aSS times.

Note) Expressed as a ratio with the number of aSS when the Si film thickness is OA (not formed) as 1.

As is clear from the table and Figure 2, the film thickness of SI is 50
When the value exceeds ;, the crystal orientation and the S value improve. On the other hand, when the Si film thickness exceeded 240 OA and exceeded 300 OA, the number of aSSs deteriorated. It is thought that if the Si film was too thick, the effect of the nonmagnetic hardened layer was weakened, leading to a worsening of the number of cBs cycles. Also, if it is over 300OA, cracks will often occur due to the difference in heat coefficient.

More than 30 GOA is not desirable.

In the above embodiment, the functions explained for the case of the Sl film,
Similar results are obtained in the case of Ti, MO, W, and Zr, and the same effects as in the above embodiments are achieved.

〔Effect of the invention〕

According to the present invention, there is provided a non-magnetic substrate and a non-magnetic hardened layer coated on the non-magnetic substrate.

sr, Ti, MOl extracted from this non-magnetic hardened layer
W.

and Zr, and a magnetic medium layer formed on the non-magnetic underlayer, the crystal orientation and magnetic properties are improved, and aSS
This has the effect of increasing the number of times and providing a highly reliable magnetic recording medium.

In addition, the thickness of the nonmagnetic underlayer made of any one of *8+e T+, Mo, W, and Zr was 50
When the range is set to 24 GOA, the above-mentioned effect becomes even greater.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a magnetic recording medium obtained according to an embodiment of the present invention, and FIGS. It is a characteristic diagram. 0)...Nonmagnetic substrate, (2)...Nonmagnetic hardened layer, (
3)...8i nonmagnetic underlayer, (4)...magnetic medium layer.

Claims (2)

[Claims] (1) A nonmagnetic substrate, a nonmagnetic hardened layer coated on this nonmagnetic substrate, and a Si, Ti coated on this nonmagnetic hardened layer.
, Mo, W, and Zr, and a magnetic medium layer covered with the nonmagnetic underlayer. (2) The thickness of the nonmagnetic underlayer made of any one of Si, Ti, Mo, W, and Zr is 50 to 2
2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a thickness of 400 Å.